Re: Sorry but 'last line is blank' doesnt wash..

Well I'm definately not at the wizard/god level, but I think I might know what's really going on. It's up to others to call it a bug or not.

I threw this in a debugger to see what exactly happens where. With this code..

my @ary=split(" ",$_) while (<DATA>);
print "@ary";
__DATA__
These are words
These are more words
[download]

I set a breakpoint upon reaching the suspect line. When it hits the line, the my variable @ary is created. It's empty. This is done before the evaluation of the expression. Unfortunately the debugger I was using won't show the reiteration of that line. But needless to say, when I stepped off that line, @ary was still empty.

Next, I used

my @ary;
@ary=split(" ",$_) while (<DATA>);
print "@ary";
__DATA__
These are words
These are more words
[download]

I set the breakpoint on the my declaration. As before, when I hit that line, @ary was created. When I left the line, it contained the last line of text, each word in an array element.

What that information, here's my opinion:

Each time the line in question is accessed, @ary is redeclared (blank). This even happens when the line is executed just for <DATA> to return false. So the last iteration redeclares @ary, there's no more DATA and the program moves on.

Is that a bug? I'll let someone else answer that :)

Rich

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Monks, I think we have a winner! by demerphq (Chancellor) on Sep 10, 2001 at 22:17 UTC
++rchiav!!! Thats sounds like a damn good analysis to me. Each time the line in question is accessed, @ary is redeclared (blank). This even happens when the line is executed just for `<DATA>` to return false. So the last iteration redeclares @ary, there's no more DATA and the program moves on. I really have to get the debugger frame of mind happening, I almost never use it, preferring copious print statements and the like, but as you have done here it can work wonders. You might not consider yourself to be god/wizard level but I think this ones worth a bunch of votes. Good play sir! Yves -- You are not ready to use symrefs unless you already know why they are bad. -- tadmc (CLPM)	[reply] [d/l]
Re: Re: Sorry but 'last line is blank' doesnt wash.. by George_Sherston (Vicar) on Sep 10, 2001 at 23:19 UTC
Very interesting. Now /me understands. In fact this is a question of how `my` works rather than how `$_ while` works (I confess I am a very recent convert to `use strict`, so this is key for me to get to grips with). I understand both better now, and I must say, at the risk of sounding like a broken record, how inspired I am by how this thread (and many others) worked. It's not just a matter of having the right answers presented clearly, but of reading them in the context of a live problem. These are lessons I shan't forget - I hope it was educational for others too. Muchas gracias to all who posted. § George Sherston	[reply] [d/l] [select]